The present invention relates generally to the field of fabricating modular assemblies. More particularly, the present invention relates to methods and apparatuses for forming electrical devices having a double-metal driven component.
Fabrication of display panels is well known in the art. Display panels may be comprised of active matrix or passive matrix panels. Active matrix panels and passive matrix panels may be either transmissive or reflective. Transmissive displays include polysilicon thin-film transistor (TFT) displays, and high-resolution polysilicon displays. Reflective displays typically comprise single crystal silicon integrated circuit substrates that have reflective pixels.
Liquid crystals, electroluminescent (EL) materials, organic light emitting diodes (OLEDs) up and downconverting phosphor (U/DCP), electrophoretic (EP) materials, or light emitting diodes (LEDs) may be used in fabricating flat-panel display panels. Each of these is known in the art and is discussed briefly below.
Liquid crystal displays uses rod-shaped molecules (liquid crystals) that flow like liquid and have the ability to bend light. The liquid crystals are typically sandwiched between two polarizing filters, horizontal and vertical. Unenergized, the crystals direct light through these two polarizing filters, allowing a natural background color to show. When energized, the crystals redirect the light to be absorbed in one of the polarizing filers, causing the dark appearance of the crossed polarizing filter to show.
Liquid crystal displays (LCDs) can be passive or active. In a passive matrix display, all of the active electronics (e.g., transistors) are outside of the display screen. LCDs may also have a passive matrix backplane which is usually two planes of strip electrodes which sandwich the liquid crystal material. However, passive matrices generally provide a lower quality display compared to active matrices. Liquid crystal materials includes, but is not limited to, twisted nematic (TN), Super TN, double STN, and ferroelectric.
In an active matrix display, the active electronics are built into each pixel within the screen. For instance, the thin-film transistors are co-located with the LCD pixels in the backplane. In particular, flat-panel displays employing LCDs generally include five different components or layers: a White or sequential Red, Green, Blue light source, a first polarizing filter, that is mounted to one side of a circuit panel on which the TFTs are arrayed to form pixels, a filter plate containing at least three primary colors arranged into pixels, and a second polarizing filter. A volume between the circuit panel and the filter plate is filled with a liquid crystal material. This material will rotate the polarized light when an electric field is applied between the circuit panel and a transparent ground electrode affixed to the filter plate or a cover glass. Thus, when a particular pixel of the display is turned on, the liquid crystal material rotates polarized light being transmitted through the material so that it will pass through the second polarizing filter. Some liquid crystal material, however, require no polarizers.
U/DCP and EP displays are formed in a similar fashion except the active medium is different (e.g., upconverting gas, downconverting gas, electrophoretic materials).
EL displays have one or more pixels that are energized by an alternating current (AC) that must be provided to each pixel by row and column interconnects. EL displays generally provide a low brightness output because passive circuitry for exciting pixel phosphors typically operates at a pixel excitation frequency that is low relative to the luminance decay time of the phospor material. However, an active matrix reduces the interconnect capacitance allowing the use of high frequency AC in order to obtain more efficient electroluminescence in the pixel phosphor. This results in increased brightness in the display.
LED displays are also used in flat-panel displays. LEDs emit light when energized. OLEDs operate like the LEDs except OLEDs use organic material in the formation of the diode.
Regardless of the type of active medium used, displays are generally comprised of at least a substrate and a backplane. The backplane forms the electrical interconnection of the display and comprises electrodes, capacitors, and transistors in at least some embodiments of a backplane.
In one typical example, the backplane may be formed by depositing blocks, using an FSA technique, into a substrate (e.g. glass); each block contains a driving circuit for driving a particular segment of the display by driving certain pixel electrodes in the display. An example of an FSA technique is described in U.S. Pat. No. 5,545,291. The pixel electrodes then control the display. For example, a capacitor is coupled to a pixel electrode by another conductor that is deposited onto the substrate. The active medium (e.g., a liquid crystal) is deposited at least on the pixel electrodes which will optically change the active medium""s properties in response to the combined voltages or currents produced by the pixel electrodes.
For each segment of the display, some pixel electrodes are dedicated to driving the images that we see on the display (e.g., numerical values or alphabetical values) and some pixel electrodes are dedicated to driving the background associated with that particular segment. There are, of course, multiple segments that control the images on the display and thus, there are also multiple pixel electrodes that drive the background of those images. However, all of the pixel electrodes that drive the background typically have the same function, i.e., to drive the background. Yet, there are multiple pixel electrodes dedicated to do the same function. The multiplicity of the pixel electrodes requires multiplicity of driving circuits or functional blocks. The multiplicity of the driving circuits or functional blocks then makes the fabrication of the display complex because more blocks and interconnections are needed.
The present invention relates to making electrical devices that require less functional blocks and less complicated interconnections especially when there are multiple segments or portions of the electrical devices that could be uniformly controlled. An electronic assembly comprises at least one object, a receiving substrate, such as a flexible receiving substrate, a bottom conducting layer, a top conducting layer, an insulation layer and electrical interconnections. The object having a first electrical circuitry therein is created and separated from a host substrate. The flexible receiving substrate has at least one recess. The bottom conducting layer is deposited over the flexible receiving substrate and the recess. The object is coupled to the receiving substrate such that the object is deposited on the bottom conducting layer and recessed within the first recess and below a surface of the receiving substrate. The insulation layer is disposed over the receiving substrate such that the insulation layer insulates the bottom conducting layer and the first object. The insulation layer includes a plurality of vias through which electrical interconnections are established. The top conducting layer is deposited over the insulation layer and is making the electrical interconnections to the bottom conducting layer and the first object through those vias.